The entanglement of assistance has been introduced with respect to some specific functions [1]}, [2]}, [3]}, [4]}. Definition (REF ) presents a general notion of entanglement of assistance for arbitrary function \(f\in \mathfrak {F}\setminus \lbrace 0\rbrace \) .
It is a dual construction to the entanglement of convex roof. Unlike the entanglement of convex roof which is an entanglement measure, the entanglement of assistance is not a measure of entanglement, as it is not monotonic under local operations and classical communications [5]}. But the entanglement of assistance describes the hidden entanglement that can be unlocked with the help of another party's local measurement and classical communication.
